* Reference: Chapter 10 of
* Jeffrey M. Wooldridge, Introductory Econometrics: A Modern Approach,
* South-Western College Publishing, 2000.
SAMPLE 1 42
READ (HSEINV.shd) year inv pop price linv lpop lprice t &
   invpc linvpc lprice_1 linvpc_1 gprice ginvpc 
SET MISSVALU=-999
SET SKIPMISS

* Example 10.7
* Equation (10.32), p. 335.
OLS linvpc lprice / LOGLOG

* Equation (10.33), p. 335.
* Generate a time trend
GENR t=TIME(0)
OLS linvpc lprice t / LOGLOG COEF=BETA STDERR=SE
* The coefficient on the time trend variable gives the
* instantaneous growth rate for the dependent variable, holding
* all other variables constant. 

* Additional Notes.
* For a coefficient a, the compound annual rate of growth is:
*     g = 100 (exp(a) - 1)
* Now denote a as the estimated coefficient and V(a) as the variance
* estimate. An estimate for g can be computed from the OLS estimation 
* results as:
*         100 (exp(a-V(a)/2) - 1)
GEN1 VA=(SE:2)**2
GEN1 g=100*(exp(BETA:2-VA/2)-1)
PRINT g
STOP